After the Austro-Hungarian Navy had filled its most urgent needs
for submarines after the outbreak of World War I, they selected the
German Type UB II design for its next group of submarines in mid
1915. Orders for the first six boats were placed in October 1915
with the Austrian firm of Cantiere Navale Triestino and
the Hungarian firm of Ganz Danubius. Two
more boats were ordered in 1916, bringing the class total to
eight.

The boats were just over 121 feet (37 m) long and were
armed with two bow torpedo tubes, a deck gun, and a machine gun. For propulsion they were
equipped with twin diesel engines for surface running and
twin electric
motors for subsurface movement. Although the class was based on
the German design, the Austro-Hungarian U-boats were heavier and
slightly faster underwater, but less heavily armed than their
German counterparts

All eight boats were commissioned into the Austro-Hungarian Navy
between 1917 and 1918 and saw active service during the war. SM U-27 and SM U-28 were
the most successful in terms of ships sunk and gross register tonnage sunk, respectively.
Two boats sank only one ship each, and a third, SM U-30, sank
no ships. U-30 was also the only boat of the class to be
lost during the war. The remaining seven were ceded to France and
Italy as war
reparations and six were scrapped by 1920; the seventh sank
while being towed to Bizerta for scrapping.

After these steps alleviated their most urgent needs,[2]
the Austro-Hungarian Navy selected the German Type UB II design
for its newest submarines in mid 1915.[4]
The Germans were reluctant to allocate any of their wartime
resources to Austro-Hungarian construction, but were willing to
sell plans for up to six of the UB II boats to be constructed under
license in Austria-Hungary.[4]
The Navy agreed to the proposal and purchased the plans from AG Weser of Bremen.[5]

Design

The U-27-class boats were coastal submarines that
displaced 264 metric tons (291 short tons) surfaced and
301 metric tons (332 short tons) submerged.[1]
The boats had a single hull with saddle tanks,[6]
and were 121 feet 1 inch (36.91 m) long with a beam of
14 feet 4 inches (4.37 m) and a draft of 12 feet
2 inches (3.71 m).[1]
For propulsion, they featured two shafts, twin diesel engines of
270 bhp (200 kW) for surface running, and twin electric motors
of 280 shp (210 kW) for submerged travel. The boats were
capable of 9 knots (16.7 km/h) while surfaced and
7.5 knots (13.9 km/h) while submerged.[1]
Although there is no specific notation of a range for the
U-27 class, the German UB II boats, upon which the class
was based, had a range of over 6,000 nautical miles
(11,000 km) at 5 knots (9.3 km/h) surfaced, and
45 nautical miles (83 km) at 4 knots (7.4 km/h)
submerged.[6]
The U-27 class boats were designed for a crew of
23–24.[1]

The U-27 class boats were armed with two 45 cm
(17.7 in) bow torpedo tubes and carried a complement of four
torpedoes. They were also equipped with a 75 mm/26
(3.0 in) deck gun and
an 8 mm (0.31 in) machine gun.[1]

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Differences from
the Type UB II submarines

Although the U-27 design was based on the German Type
UB II submarine, there were some differences between the two
designs.[Note 3]
The Austro-Hungarian boats were slightly heavier than their German
counterparts, by only 1 metric ton (1.1 short tons) while
surfaced, but by 9 metric tons (9.9 short tons) while
submerged. The UB II boats were shorter by about 3 feet
(0.91 m) in length, but nearly identical in beam and draft.
Both types of submarines were rated at the same 9 knots
(17 km/h) on the surface, but the Austro-Hungarian boats were
reported as over 1.5 knots (2.8 km/h) faster underwater
even though the electric motors of the two classes had comparable
power output. The German boats were more typically more heavily
armed than their Austro-Hungarian cousins, and featured two larger
torpedo tubes—50 cm (19.7 in) vs. 45 cm
(17.7 in)—and many sported a larger deck gun—88 mm
(3.5 in) vs. 75 mm (3.0 in).[7]

Construction

With the plans purchased, the Austro-Hungarian Navy began the
intricate political negotiations to assign the six boats—to be
designated U-27 to U-32—between Austrian and
Hungarian firms.[4][Note 4]
Of the initial order of six boats, two were allocated to the
Austrian firm of Cantiere Navale Triestino
(CNT) operating out of the Pola Navy Yard,[Note
5] and the balance to the Hungarian firm of
Ganz Danubius in Fiume.[4]
The Navy ordered the first six boats of the class on 12 October
1915.[8]

The first six boats were all laid down between late
1915 and early 1916.[4]
Later in 1916, the seventh boat of the class, U-40, was laid down,
after having been presented to the Navy as a gift by the
Österreichischen Flottenverein, and an eighth, U-41,[4]
as a replacement for U-6,[5]
which had been lost in May.[3]
The seventh and eighth boats were constructed by CNT at the Pola
Navy Yard.[3]
Shortages of labor and materials plagued subcontractors and,
consequently, the delivery dates for the boats were not met.
However, the first six boats had all entered service by the middle
of 1917.[4]

The first of the class to be launched was U-27 on 19 October
1916, followed closely behind by U-29 three days
later. The final boat launched was U-41 on 11 November
1917.[1]
The U-27 class boats were the last domestically built
submarines completed for the Austro-Hungarian Navy.[8]

Service
career

All the boats of the U-27 class, the most numerous of
all the Austro-Hungarian submarine classes,[8]
saw active service,[1]
and all but one boat had wartime successes;[9]U-30 sank no ships
during her career,[9]
and disappeared after the end of March 1917, the only boat of the
class to be lost during the war.[1]U-31 and
U-41 also had little success, each credited with sinking a
single ship. At the other end of the spectrum, U-27, the
lead
boat of the class, sank the largest number of ships, 33, and U-28 sank the
greatest amount of tonnage, 44,743 GRT.[9]

At the end of the war, U-27 and U-32 were
surrendered at Pola, while U-28 and U-40 were
surrendered at Venice. All four of these boats were ceded to Italy
as war
reparations and were scrapped by 1920. U-29,
U-31, and U-41 were half of the six submarines at
Cattaro,[Note
6] and were all awarded to France. The boats
were towed from Cattaro to Bizerta, but U-29 foundered en
route; U-31, U-41, and the others were scrapped
within twelve months of their arrival there.[10]

Class
members

SM
U-27

U-27, the lead boat of the class, was built by the
Austrian firm of Cantiere Navale Triestino
(CNT) at the Pola Navy Yard and launched on 19
October 1916.[1]
She was commissioned on 24 February 1917.[11]
During the war, she sank the British destroyer Phoenix, damaged the
Japanese destroyer Sakaki, and sank or captured 34 other
ships totaling 14,386 GRT.[12]U-27 was surrendered at Pola at war's end and handed over to Italy as a war reparation in 1919 and was broken up
the following year.[10]Conway's All the World's Fighting Ships, 1906–1921 calls
U-27 Austria-Hungary's "most successful submarine".[13]

SM
U-28

U-28 was built by CNT at the Pola Navy Yard and
launched on 8 January 1917.[1]
The boat was commissioned on 26 June 1917.[14]
Under the command of Zdenko Hudeček, U-28 sank ten ships
totaling 44,743 GRT and damaged another 5,592 GRT.[15]
She was surrendered to the Italians at Venice in 1919 and scrapped
in 1920.[10]

SM
U-29

U-29 was built by the Hungarian firm of Ganz Danubius at Fiume and launched on 21
October 1916.[1]
She was commissioned on 21 January 1917,[16]
the first of the class to be commissioned. Under commander Leo
Prásil, U-29 sank three British steamers (14,784 GRT)
and damaged the British protected cruiser Edgar.[17]U-29 was at Cattaro at the end of the war and awarded to
France as war reparation in 1920, but foundered while under tow to
Bizerta
for scrapping.[10]

SM
U-30

U-30 was built by Danubius at Fiume, launched on 27
December 1916,[1]
and commissioned on 17 February 1917.[18]
The boat, under the command of Linienschiffsleutnant Friedrich
Fähndrich, sailed from Cattaro on 31 March 1917 and was never
heard from again.[19]U-30 sank no ships during her brief career.[20]

SM
U-31

U-31 was built by Danubius at Fiume and launched on 28
March 1917.[1]
She was commissioned on 24 April 1917.[21]
In addition to damaging the British light cruiser Weymouth in October 1918,
U-31 sank one other ship, an Italian vessel of
4,021 GRT.[22]
She was scrapped in Bizerta after she was awarded to France in
1920.[10]

SM
U-32

U-32 was built by Danubius at Fiume and launched on 11
May 1917.[1]
The boat was commissioned on 29 June 1917.[23]U-32 hit five ships of 6,788 GRT, sinking four and
damaging one.[24]
At Pola at war's end, the boat was handed over to Italy and
scrapped in 1920.[10]

SM
U-40

U-40 was ordered after the funds to purchase the boat
were presented by the Östereichischen Flottenverein as a
gift to the Austro-Hungarian Navy. She was built by CNT at the Pola
Navy Yard, launched on 21 April 1917.[1]
and commissioned on 4 August 1917.[25]
During the war, U-40 sank two ships and damaged two
others, hitting a total of 14,979 GRT Commonwealth
shipping.[26]
The Italian destroyer Ardea claimed to have sunk
U-40 in a depth charge attack on 26 April 1918,[27]
but the boat was surrendered to Italy at Venice in 1919 and broken
up.[10]

SM
U-41

U-41 was ordered as a replacement for SM U-6 which had
been sunk in May 1916.[5] She
was built by CNT at the Pola Navy Yard and launched on 11 November
1917. During construction, U-41 was lengthened about
30 centimetres (12 in) to accommodate the diesel engines on
hand that were to have been installed in U-6.[1]U-41 was commissioned on 19 February 1918,[28]
the last boat of the class, and the last Austro-Hungarian boat
completed and commissioned into the Austro-Hungarian Navy.[5]U-41 sank a single French steamer of 4,604 GRT during
her short wartime career,[29]
and was at Cattaro at war's end.[10]
She was ceded to France in 1920 and towed to Bizerta, where she was
scrapped within the year.[10]

^
By this time, the CNT shipyards at Monfalcone had been
overrun by the Italian
Army. See: Baumgartner and Sieche, as excerpted here (reprinted and translated into English by
Sieche). Retrieved 1 December 2008.

^
The other three submarines were U-22, U-43, and U-47. See: Gibson and Prendergast,
pp. 388–89